This section is intended to provide a background or context to the invention recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
Alkenes are important hydrocarbon intermediates used in the production of various polymers and liquid fuels (i.e. isobutene dimerization to isooctane). Dienes (e.g., 1,3-butadiene) and acetylenes (e.g., alkynes, vinylacetylene) are common unsaturated olefin feedstock contaminants that decompose and deactivate catalysts used in polymerization and olefin dimerization/oligomerization processes. Thus, selective removal via catalytic hydrogenation of these unsaturated dienes and acetylene contaminants is a critical processing/purification step in the industrial refining of mono-olefin feedstocks (e.g., ethylene, propylene and butenes). More specifically, highly selective hydrogenation of dienes and acetylenes (e.g., 1,3-butadiene and vinylacetylenes to butenes) with minimal hydrogenation of mono-olefins to the lower value alkane products is warranted since chemoselective catalysts that completely discriminate the contaminants from the hydrogenation-sensitive mono-olefin are extremely rare. For example, a catalyst that can semi-hydrogenate 1,3-butadiene and vinylacetylene contaminants to mono-olefins (1-butene) in a feedstock comprised mainly of the mono-olefin (1-butene) is one way to decrease the concentration of the unwanted contaminants, and increase the amount of desirable mono-olefin component. As a result, the overall efficiency of olefin polymerization and dimerization/oligomerization processes would also improve.
Conventional diene and acetylenes hydrogenation techniques employ multimetallic nanoparticles (i.e. palladium (Pd), platinum (Pt), and silver (Ag)) that are often promoted by other transition metals, such as nickel, which is toxic. Because these techniques use bulk catalytic structures (i.e. nanoparticles), the overall atom efficiency of the hydrogenation catalysts is low. Other strategies may involve poisoning nanoparticle or bulk active surfaces with organosulfur ligands that are labile, impacting long-term catalyst stability. Moreover, most hydrogenation catalysts for dienes and acetylenes are used at low temperatures (e.g., 50° C.) due to their susceptibility to coke deposition, which blocks catalytic sites and ultimately results in catalyst deactivation. Since most of these catalysts are mainly evaluated at lower temperatures, low diene and acetylene conversions are generally observed.
A need exists for improved technology, including a selective catalyst for hydrogenation of dienes (e.g., 1,3-butadiene) and acetylenes, and a method for hydrogenation of these compounds.